This study compares the antioxidant capacities of the xanthone family and analyzes structure‐activity relationship. Thirty xanthones with various structural features were selected as the references and their antioxidant capacities were determined using the 1,1‐diphenyl‐2‐picryl‐hydrazyl radical (DPPH•) scavenging assay. The results of the assay indicated that these xanthones could scavenge the DPPH• in a dose‐dependent manner. It was found that their Trolox equivalent antioxidant capacity (TEAC) values varied by the presence or absence of hydroquinone (or catechol) group within the molecule. The former 15 xanthones (1‐15, TEAC=2.030‐0.568) with hydroquinone (or catechol) pattern possessed much higher TEAC values than the latter 15 xanthones (16‐30, TEAC=0.019‐0.002) without hydroquinone (or catechol) pattern. It was concluded that the presence of the hydroquinone (or catechol) group governs the antioxidant capacity of xanthone family. Other structural factors, such as isoprenylation, methylation, and glycosidation, play a minor role, unless they remove the hydroquinone (or catechol) pattern. These findings can be used to directly predict the antioxidant capacity of xanthone.

中文翻译：

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抗氧化剂氧杂蒽酮家族的1,1-二苯基-2-吡啶基-肼基自由基（DPPH•）清除能力的比较研究

本研究比较了the吨酮家族的抗氧化能力，并分析了其构效关系。选择了三十种具有不同结构特征的氧杂蒽酮作为参考，并通过1,1-二苯基-2-吡啶基-肼基自由基（DPPH•）清除试验测定了它们的抗氧化能力。分析结果表明，这些氧杂蒽酮可以剂量依赖的方式清除DPPH•。发现它们的Trolox等效抗氧化剂容量（TEAC）值因分子中是否存在对苯二酚（或邻苯二酚）基团而异。具有对苯二酚（或邻苯二酚）模式的前15个氧杂蒽（1-15，TEAC = 2.030-0.568）具有比后15个氧杂蒽（16-30）高得多的TEAC值，TEAC = 0.019-0.002）而没有氢醌（或邻苯二酚）模式。结论是对苯二酚（或邻苯二酚）基团的存在决定了黄酮家族的抗氧化能力。除非异戊二烯化，甲基化和糖苷化等其他结构性因素消除了对苯二酚（或邻苯二酚）模式，否则它们的作用较小。这些发现可用于直接预测x吨酮的抗氧化能力。